A Patent Document 1 describes a temperature control device for controlling a temperature of a heating plate which a semiconductor wafer is placed. In this device, the plate is heated by a heater and as a result, the wafer placed on the plate is heated. This device controls the heating operation of the heater such that the plate temperature becomes a target temperature.
In the device of the Document 1, when the plate is subject to a disturbance, the plate temperature may become higher or lower than the target temperature (hereinafter, this target temperature may be referred to as —initial target temperature—).
If the target plate temperature is temporarily decreased just before the plate temperature becomes higher than the initial target temperature, the heat amount given from the heater to the plate decreases and thereby, it is restricted that the plate temperature becomes higher than the initial target temperature.
On the other hand, if the target plate temperature is temporarily increased just before the plate temperature becomes lower than the initial target temperature, the heat amount given from the heater to the plate increases and thereby, it is restricted that the plate temperature becomes lower than the initial target temperature.
Therefore, if the target plate temperature is changed in opposite phase manner relative to the plate temperature change, which may occur in case that the target plate temperature is maintained at the initial target temperature when the plated is subject to the disturbance, the plate temperature is maintained at the initial target temperature even when the plate is subject to the disturbance.
In the device of the Document 1, a disturbance is forcibly given to the plate in the state where the plate temperature is controlled at the initial target temperature and the plate temperature change pattern at this time is measured.
A temperature change pattern at the phase opposite to that of the measured temperature change pattern is acquired as a target temperature change pattern for the plate subject to the disturbance (i.e. the disturbance forcibly given to the plate in order to measure the plate temperature change pattern).
When the plate is subject to the same disturbance as the aforementioned disturbance, the target plate temperature is changed according to the acquired target pattern to maintain the plate temperature at the initial target temperature.
That is, the Document 1 teaches that the temperature change pattern of the plate subject to the disturbance is predicted to maintain the plate temperature at the initial target temperature by changing the target plate temperature according to the predicted pattern.